1. Field of the Invention
The invention relates to a system for providing control of the position parameters of a movable device.
2. Description of the Prior Art
Such a system is known, for example, from the publication "Clinac 6/100" by Messrs. Varian (RAD 1826 A 2/79). In this publication, the spatially movable device to be controlled consists of a Linac and a surgical bed. A manual unit of the system is disclosed on page 6 of this publication. One of the disadvantages of this unit is that both hands are needed to operate it. The patient can therefore not be looked after while the Linac or the surgical bed is being adjusted.
From the publication "Asklepitron-45" by Messrs. BBC (CH-E 6.0017.1.E) a control unit for a betatron and a surgical bed is known, which is permanently installed on a pedestal. The so-called "deadman's requirement", namely that the capability for initiating a change in parameters must be provided via two mechanically and electrically separate signal circuits, is not met in this system. In similar control units a foot pedal is used to meet the deadman's requirement.
From the publication "Therasim 720" by Messrs. AECL (Med. 54 3/72), a system for controlling a therapy unit and a surgical bed is known in which a manual unit, an input unit and an electronic process control unit are shown. Both hands are needed to operate the manual unit.
All systems described above have the additional disadvantage that a direct comparison between the parameter values set and the nominal values is not possible.
Another disadvantage consists in the fact that the keys of the control unit can be accidentally or even deliberately blocked. When the control units do not have the deadman's function, serious consequences can result for the patient, especially in the case of systems without protection against accidental contact in which, for example, all parameter changes are immediately interrupted if the radiator head is touched.